1、Manual of PetroleumMeasurement StandardsChapter 3Tank GaugingSection 5Standard Practice for Level Measurement of Light Hydrocarbon Liquids Onboard Marine Vessels by Automatic Tank GaugingFIRST EDITION, MARCH 1997REAFFIRMED, FEBRUARY 2013Manual of PetroleumMeasurement StandardsChapter 3Tank GaugingSe
2、ction 5Standard Practice for Level Measurement of Light Hydrocarbon Liquids Onboard Marine Vessels by Automatic Tank GaugingMeasurement CoordinationFIRST EDITION, MARCH 1997REAFFIRMED, FEBRUARY 2013SPECIAL NOTESAPI publications necessarily address problems of a general nature. With respect to partic
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14、n Petroleum InstituteiiiFOREWORDThis publication covers standard practice for level measurement of light hydrocarbon liq-uids onboard marine vessels by automatic tank gauging. The light hydrocarbon liquids cov-ered in this standard may be pressurized or refrigerated, or both. The light hydrocarbonli
15、quids covered include: liquefied petroleum gas (LPG), natural gas liquid (NGL) and otherpetrochemical liquids where the storage and transportation requirements and the methods ofmeasurement are similar to that for LPG and NGL gauging.API publications may be used by anyone desiring to do so. Every ef
16、fort has been made bythe Institute to assure the accuracy and reliability of the data contained in them; however, theInstitute makes no representation, warranty, or guarantee in connection with this publicationand hereby expressly disclaims any liability or responsibility for loss or damage resultin
17、gfrom its use or for the violation of any federal, state, or municipal regulation with which thispublication may conflict.Suggested revisions are invited and should be submitted to the Measurement Coordinator,Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W.,Wa
18、shington, D.C. 20005.vCONTENTSPage1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 GEN
19、ERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 ACCURACY REQUIREMENT. . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.1 Inherent Error of ATGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.2 Calibration Prior to Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.3 Shipy
21、ard Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.4 Error Caused by Installation and Change of Operating Conditions . . . . . . . . . . . 34.5 Use of ATGs in Custody Transfer Service . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . 35 INSTALLATION REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.2 Mounting Location . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.3 Manufacturers Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.4 Installation of ATGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 SETTI
24、NG OF ATG AT SHIPYARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.1 Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.2 Setting ATGs . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . . . . . . . 57 ONBOARD VERIFICATION OF ATGs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.2 Verification Pr
26、ocedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.3 Procedure for Applications Where Manual Gauging is Practical. . . . . . . . . . . . . 67.4 Procedure for Applications Where Manual Gauging is Not Practical . . . . . . . . . 78 SUBSEQUENT ATG VER
27、IFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 ATG VERIFICATION RECORDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 710 DATA COMMUNICATION AND RECEIVING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Standard Pract
28、ice for Level Measurement of Light Hydrocarbon LiquidsOnboard Marine Vessels by Automatic Tank Gauging1 ScopeThis standard covers accuracy, installation, calibration andverification of automatic tank gauges (ATGs) in custodytransfer application in which the ATG is used for measuringthe level of ligh
29、t hydrocarbon liquids, such as liquefied petro-leum gas (LPG) transported aboard marine vessels (i.e., tank-ers and barges). The light hydrocarbon liquids covered in thisstandard may be pressurized or refrigerated, or both.This standard is applicable to natural gas liquid (NGL) andother petrochemica
30、l liquids where the storage and transporta-tion requirements and the methods of measurement are simi-lar to those for LPG gauging.This standard is not applicable to cryogenic liquids (below100 F) such as liquefied natural gas (LNG).Although the accuracy of marine automatic tank gauging isaffected by
31、 some of the limitations described in Manual ofPetroleum Measurement Standards (MPMS),Chapters 3.3and 3.4, ATGs onboard LPG marine carriers can be used incustody transfer when no better, alternative measurement isavailable.The standard also covers the requirements for data collec-tion, transmission,
32、 and receiving.This standard may involve hazardous materials, operations,and equipment. This standard does not purport to address allof the safety problems associated with its use. It is the respon-sibility of the user of this standard to establish appropriatesafety and health practices and determin
33、e the applicability ofregulatory limitations prior to use.2 ReferencesAPIManual of Petroleum Measurement Standards(MPMS):Chapter 1, “Vocabulary”Chapter 2, “Tank Calibration”Chapter 3, “Tank Gauging”Chapter 7, “Temperature Determination”Chapter 12, “Calculation of Petroleum Quantities”Chapter 17, “Ma
34、rine Measurement”GPA1Standard 8195, Standard for Converting Net Vapor SpaceVolumes to Equivalent Liquid Volumes3 GeneralThis section is applicable to all types of ATGs used inmarine vessels carrying light hydrocarbon liquids. Safety pre-cautions are listed separately from general precautions thataff
35、ect accuracy or performance.3.1 SAFETY PRECAUTIONSThe following recommended practices and guidelines onsafety should be followed:a. API Recommended Practice 500, Classification of Loca-tions for Electrical Installations at Petroleum Facilities.b. API Recommended Practice 2003, Protection AgainstIgni
36、tion Arising Out of Static, Lightning and Stray Currents.c. ISGOTTInternational Safety Guide for Oil Tankers andTerminals.d. IMOInternational Code for Construction and Equip-ment of Ships Carrying Liquefied Gases in Bulk(IGC Code),Chapter 13.1, Instrumentation (Gauging, Gas Detection).e. US Coast Gu
37、ard (USCG) regulation33 CFR, Part 153.f. USCG regulation46 CFR, Part 39.20.g. USCG Marine Safety Center NVIC 2-89, “Basic Guid-ance for Electrical Installations on Merchant Vessels.”Other applicable safety codes and regulations should becomplied with.3.1.1 Electrical SafetyAll electric components of
38、 a marine ATG for use in electri-cally classified areas should be appropriate to the classifica-tion of the area and should conform to appropriate national(UL, FM, FCC, NEC, etc.) electrical safety standards, and/orinternational (IMO, IEC, CENELEC, ISO, and so forth)marine electrical safety standard
39、s.3.1.2 Equipment Precautions3.1.2.1All marine ATG equipment should be capable ofwithstanding the pressure, temperature, operating, and envi-ronmental conditions likely to be encountered in the service.3.1.2.2Measures should be taken to guarantee that allexposed metal parts of the ATG and its associ
40、ated equipmentshould have the same electrical potential as the tank.3.1.2.3All marine ATG equipment should be maintainedin safe operating condition, and manufacturers maintenanceinstructions should be complied with. As an alternate, thesensors should be intrinsically safe.Note 1: The design and inst
41、allation of ATGs may be subject to the approvalof a national measurement organization, which will normally have issued atype approval for the design of the ATG for the particular service for which itis to be employed. Type approval is normally issued after an ATG has beensubjected to a specific seri
42、es of tests. Type approval is also based on installa-tion in a preapproved manner. Type approval tests may include the following:1Gas Processor Association, 6526 East 60th Street, Tulsa, Oklahoma 741452 API CHAPTER3.5visual inspection, performance, vibration, humidity, dry heat, inclination,fluctuat
43、ions in power supplies, insulation, resistance, electromagnetic com-patibility, high voltage, pressure compatibility, and material certificates. Fur-ther fireproof certificates may be required.Note 2: The design and installation may be subject to the approval of nationalsafety organizations dealing
44、with pressure vessels and the application ofmeasuring instruments.3.1.3 General PrecautionsThe following general precautions apply to all types ofmarine ATGs and should be observed where they areapplicable.3.1.3.1The measurement of pressure and temperature ofthe vapor in the tank, liquid temperature
45、, or any other rele-vant parameter should be time correlated with the tanklevel measurement. The tank liquid temperature should berepresentative of the liquid contents. The cargo tankshould be isolated from other tanks and lines when takingATG readings.3.1.3.2All information obtained from the measur
46、ementin a bulk transfer should be recorded promptly as it istaken.3.1.3.3Whenever a determination of the contents of atank is made before the movement of a bulk quantity of liq-uid (opening gauge) and after the movement of a bulk quan-tity of liquid (closing gauge), the same general proceduresshould
47、 be used to measure the tank level.3.1.3.4All parts of the ATG in contact with the product orits vapor should be chemically compatible with the product, toavoid both product contamination and corrosion of the ATG.3.1.3.5ATGs should have sufficient dynamic response totrack the liquid level during max
48、imum tank filling or empty-ing rates.3.1.3.6Marine ATGs should be designed to withstanddamage caused by waves in the tanks due to ship move-ment.Note 1: This protection may require mounting the ATGs in perforated or slot-ted still pipes.Note 2: Alternately, this protection may require that the mecha
49、nical float typebe raised to a “store” position when it is not being used.3.1.3.7Following the transfer of product, the tank shouldbe allowed to settle so that the liquid surface is sufficientlyquiescent before the tank level is measured.3.1.3.8Following a rapid change in the ambient condi-tions, or operation of the liquefaction plant onboard thevessel, the liquid surface may show temporary instability(such as boiling). The level measuring equipment shouldbe capable of detecting the liquid surface even when it isunstable, and it should be capable of providing a readingcorrespon
